Linkage 1/8: Tetrapod Tracks & Cell-Phone Therapy

A bit of a firestorm with local significance was stirred up this week when a paper published in Nature purported to reset the clock on when marine animals took their first step out of water. Grzegorz Niedzwiedzki and colleagues from Warsaw and Sweden presented a fossil “trackway” made up of what the team identified as several hand and footprints from a tetrapod four-limbed vertebrates thought to be a key step in evolution from marine animals to land dwellers. The tracks, found in south-eastern Poland in a layer dated as 395 million years old (video), reveal some fascinating details in the authors’ analysis, including distinct hand and foot prints, toes and ankles – all critical aspects of the transition from fin to limb. It’s also the earliest known evidence for a tetrapod, predating fossil findings of “fish-with-limbs” such as Tiktaalik by nearly 20 million years.

While some are convinced of these conclusions, others are skeptical. Tiktaalik, discovered in 2004 in far northern Canada by a team led by University of Chicago paleontologist Neil Shubin, remains the earliest known tetrapod fossil, a remarkably complete specimen that clearly shows limb-like bone structure. Footprints, on the other hand, are acceptable as paleontological evidence, but much more open to question. Indeed, no tetrapod fossils – or any fossils, for that matter – were found near the trackway, which the authors attribute to the soil being a poor environment for preserving skeletons. Nevertheless, in a news article accompanying the Nature paper, other paleontologists express caution in accepting the veracity of the trackway fossil, and Phillippe Janvier of the Muséum National d’Histoire Naturelle in Paris suggested “a risk” that natural processes could have produced track-like markings.

Shubin, currently on sabbatical writing the follow-up to this award-winning Your Inner Fish, wasn’t immediately available for comment. But when he’s back, ask him what he thinks of the new discovery and how it changes our view of early tetrapod evolution.

The Cell Phone Treatment

In an almost too-weird-to-be-true piece of science news this week, a story started kicking around that the type of electromagnetic fields (EMFs) generated by cell phones was found to be effective at protecting against or even reversing the effects related to Alzheimer’s disease in mice. Studies of cell phone radiation – usually focused on proving that the phones’ electromagnetic waves cause harm – are notoriously unreliable. Time and again, studies have shown these waves do not cause brain tumors or other diseases…but in looking for damage from cell phone use, were scientists overlooking benefits?

That’s the suggestion of an intriguing paper from researchers at the Florida Alzheimer’s Disease Research Center, who published a paper on the effects of electromagnetic fields upon a mouse model of the neurodegenerative disorder. In a rare move, the paper begrudgingly admits that the authors set out to find a damaging effect of EMFs, but instead of decreased cognitive function in their mice, they found an improvement, both in mice genetically engineered to overexpress amyloid-beta (a protein implicated in Alzheimer’s) and normal mice. One hour a day of exposure to an electromagnetic field similar in strength to what cell phones put out – albeit enveloping a mouse’s entire body instead of just its head – led to better performance on a maze task when compared to mice who did not receive EMF exposure.

But before you start using the study as an excuse to spend an hour on the phone each night, there’s a whole freight train of caveats in the paper. For one, the study was in mice, and partially transgenic mice at that. For two, the mouse model of Alzheimer’s disease is imperfect, only overexpressing amyloid-beta without recreating some other characteristics of human Alzheimer’s disease. For three, EMF exposure was different than humans would experience (unless they sit in a Faraday cage once a day) and the fields themselves may not penetrate human skulls the same way as they do mouse skulls. That all adds up to the inevitable “further testing needed,” but in the meantime, it’s nice to see cell phones getting some good health press.

Miscellaneous Linkage

Partially because I used to do research on the role of nicotine receptors in brain circuits related to addiction, I was fascinated by this report that cocaine dealers are lacing the drug with a de-worming agent that just happens to be a nicotine receptor agonist. Do narcotics kingpins keep up with neuroscience literature?

The rampant disappearance of bee colonies in 2006 is one of my favorite recent scientific mysteries, with theories ranging from a new bee virus to (again) cell phone radiation. As relayed by Wired Science, the true culprit may be much more mundane: all of the above. Well, except for cell phone towers, that’s just crazy.

“The question of how a baseball player knows where to run in order to catch a fly ball has baffled psychologists for decades.” That’s the kind of teaser I like to see, and it belongs to this excellent Cognitive Daily post on a study about how outfielders catch fly balls that employed exciting things like virtual reality and math.